Spin offs have been around since the fifties, thing is they are rarely any good, the original idea doesn't expand enough. However they continue to be made. Perhaps the greatest of all spin offs is Frasier. Excellent and eminently watchable, it took the intellectual approach and made a show as great if not better than the show from which it came; Cheers.
Here a selection of spin offs for your delectation with the progenitor named.
The bad
The green green grass-Only fools and Horses
the Flintstones kids-The Flintstones (Also spawned Pebbles and Bam Bam)
The mediocre
George & Mildred-Man about the House (Also spawned Robin's nest)
The okay
Laverne and Shirley - Happy Days (also spawned Mork & Mindy and Joanie Loves Chaici)
Beverley Hills Buntz-Hill Street Blues
Mrs Columbo-Columbo
Going Straight-Porridge
The New Phil Silvers show-The Phil Silvers show AKA Sgt Bilko (Top Cat was based on this show and featured vocals from some of the original cast)
The Good
Rhoda-The Mary Tyler Moore Show (also spawned Lou Grant and Phylis)
And The Great
Frasier-Cheers